The invention relates to a video system for displaying image data comprising a server, the server having a coder device which can be operated in a number of operating modes as the active operating mode, wherein the coder device is designed for coding video data in accordance with the active operating mode and for outputting coded transmission data, and comprising a client, wherein the client can be connected to the server via a network and wherein the client is designed for the requesting, the further processing and the displaying of the coded transmission data by the coder device in a session. The invention also relates to a method for displaying image data, to a computer program and to a coder device.
In the meantime, it is customary to store image data such as, for example, video sequences on servers and to load these as required by means of a client, which is connected to the server, via a network and display them on the client.
Since the image data are to be retrieved flexibly, it must be ensured that a retrieval of the image data can always take place with a good quality corresponding to the data transmission rate even in the case of network connections with different data transmission rates. The data transmission rates extend, e.g., from 144 kbit/s in the case of an ISDN link up to 1000 Mbit/s in the case of a 1000-Mbit Ethernet network. To transmit the image data without latency and judder especially in the case of bandwidth-limited network connections, it is customary to compress the image data in different ways, the different ways of compression differing by the bit rate needed for the transmission of the compressed image data. If then a client is connected to the server via a network connection with a low data transmission rate, it is provided with the compressed image data at a low bit rate. If, in contrast, the data transmission rate of the network connection is high, the client receives the compressed image data at a correspondingly higher bit rate and thus in a higher image quality.
Such a method for transmitting image data is represented, for example, in printed document US2011/0225315A1 which may form the nearest prior art. In this document, a server-client system is described, the server supplying the client with a stream of image data. The image data are stored in the server in various versions, the versions differing in their bit rate and thus in their quality. During the transmission of the image data, a transmission buffer in the server is observed, the current version of the image data being retained or a version of the image data having a higher or lower bit rate being selected in dependence on the filling level of the transmission buffer.